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Seaview Wastewater Treatment Plant

The Seaview Wastewater Treatment Plant serves a population of about 160,000 in Upper Hutt, Lower Hutt and  Wainuiomata. The wastewater is treated or cleaned  through a series of screens, tanks, bioreactors, clarifiers and ultraviolet treatments before being discharged into the open sea near near Pencarrow Head/ Te  Raeakiaki where it is quickly diluted.

For more information on how wastewater is treated, go to the treatment process. 

One of the nine resource consents permitting the operation of the plant, consent ‘WGN120142 [33408] Discharge Treated Wastewater to Stream ' expired in 2018. Prior to the expiry of this consent, Hutt City Council applied to Greater Wellington Regional Council (GWRC) for a new consent to temporarily discharge treated wastewater  to the Waiwhetū Stream. While the reconsenting is underway, we continue to operate under the existing consent.

In general, the consents allow Hutt City Council to:

  • discharge treated and partially treated effluent through an existing outfall,
  • discharge mixed disinfected, treated and milli-screened wastewater during and/or immediately after heavy rainfall,
  • discharge mixed disinfected, treated and milli-screened wastewater during maintenance,
  • discharge of contaminants to the air,
  • and to occupy the stream and coastal marine area with an outfall structure.


Join the Seaview mailing list 

If you want to receive notifications and updates about the plant, please email

Seaview Wastewater Treatment Plant monthly newsletter

 For more information about plant activity and projects please go here

Odour treatment

Work is continuing to improve the capture of odours beyond the plant boundary.

Find out more about what’s planned and underway on the project page

The latest updates are available here

Investigation Reports

Seaview Wastewater Treatment Plant - Odour Investigation - June 2023
Seaview Wastewater Treatment Plant -Biofilter Flow Assessment -March 2024

Making a complaint

If you have a complaint about Wellington Water directly, please call 04 912 4470 or email to access our free complaints process.

After hours, please contact the Hutt City Council Call Centre on 04 570 6666 / 0800 488 824.

Greater Wellington Regional Council is the regulatory agency for reporting airborne discharges 0800 496 734.  

Complaints to the Seaview Wastewater Treatment plant can be sent to the following contact details: 

First point of contact: Veolia Duty Manager - Call 0800 928 371. 

Veolia's Duty Manager contact number operates 24/7 as such complaints can be directly forwarded to them especially if the complaint is urgent and/or happened after office hours. 

When a complaint is received, the following information will be recorded: 

    • Name 

    • Contact details of the customer 

    • Nature of the complaint 

    • Date and time 

    • Location 

Complaints shall be actioned within 24 hours upon receipt and the records being written to the plant's operational incident log.  Odour and/or wastewater discharge complaints will be forwarded to the regional council.

Plant performance monthly dashboard

Current Status: Non- compliant 
Period: March 2024 


The plant remains non-compliant for faecal coliforms (90-day, 80th percentile limit) since 30 September. Improvements to the biological process and mechanical issues in the UV systems are being addressed to return the plant back to compliance as soon as possible.


There were two discharges in March. The discharge on 4 March was due to wet weather flows (fully treated into Waiwhetu Stream) and the 8 March discharge occurred due to a power outage. This discharged to the coastal marine area at Pencarrow.

Please Explain letter Issued

Greater Wellington Regional Council issued a please explain letter in relation to the discharge that occurred on 8 March. A response will be provided within the required timeframe.

Odour complaints:

The plant received 16 odour complaints in March. 

Items of significance:

Odour Treatment prioritisation

Hutt City Council has requested the project team urgently revise plans to support fast track delivery for the odour improvement works needed at the plant. Cost estimates and Project Management Plans are currently being prepared for the proposed renewals and upgrades.

Community Liaison Group (CLG) Meeting

The annual CLG took place on 21 March covering plant performance and consent compliance for the last financial year. Updates were also provided on current performance and an update on the odour management project. The meeting minutes will be available on the Wellington Water website in April for public perusal.

Odour Treatment

What has been completed:

The project webpage has been updated with current information to improve the user experience and better inform the public.

Replacement of Biofilter material is complete. Leak repair and cleaning of foul air ducting has been undertaken.

A project brief for the renewal of the odour control system of the site has also been completed, incorporating the recommended actions from the investigation reports.

What is currently in progress:

A further report into the effectiveness of the media replacement has been commissioned.

Procurement plans being finalised for the 2024 winter biofilter works along with design work that will undergo review.

Project Management Plan (PMP) was submitted in March and is now under review. This outlines the timeframes for the odour management system upgrades. The odour scouting programme continues.

Resource consents

Resource consent reports

Te Whatu Ora - Health New Zealand statement on the use of the treatment plant deodoriser


Potential health concerns associated with exposure to quaternary ammonium compounds are most likely associated with direct contact with undiluted product i.e. the staff preparing the solution.  Staff exposure risk is managed by following the correct health and safety procedures. Quaternary ammonium compounds are often part of household cleaning and disinfection products and so exposure to the public is relatively common.  Given the level of dilution of the product used in the cannon, and the distance between the placement of the cannon and potential locations for public exposure (typically this type of cannon dispersal method has an estimated droplet range of 50-100 metres) that effectively dilutes the strength further, we would not expect this to represent a health risk for the general public.  

Te Whatu Ora - Health NZ

April 2023

Seaview Wastewater Plant Community Liaison Group Meeting - March 2024

Thursday, March 21, 2024

The following is a summary of the annual CLG . You can view the full minutes here

In attendance with residents, Te Rūnanganui o Te Āti Awa ki te Upoko o Te Ika a Māui, Waiwhetu marae and Wellington Tenths Trust/Palmerston North Māori Reserve Trust. On behalf of Hutt City Council Brady Dyer attended with Wellington Water staff and representatives from Veolia (plant operator), Regional Public Health and Greater Wellington Regional Council.

The meeting was chaired by Andrew Freeman an independent facilitator.  

Wellington Water GM Network Management Jeremy McKibbin opened the meeting acknowledging the ongoing odour issues associated with the plant and the impacts on the community.

Mr McKibbin provided an update on the biofilter media replacement and the plans to renew the plenum pipework underneath the structure this winter, as the next stage of works to improve the odour issue.

He acknowledged Council for their proactive approach to addressing issues at the plant through funding and encouraged the community to give their feedback to the Council LTP in April.

Steve Hutchison, Chief Advisor Wastewater, took the audience through a stage-by-stage process of the plant and how wastewater is treated. This discussion included reference to potential sources of odour during the plant’s treatment process.

The meeting was then introduced to Linda Fairbrother who is leading the odour management project. During this segment, the audience were informed of future planned upgrades and renewals for the plant and its current aging assets. These works are expected to address not only odour management but also help improve the plant’s overall performance.

Joemar Cacnio (Wellington Water) completed the presentations with an annual overview of the plant’s performance relating to consent compliance. Greater Wellington Regional Council (Amanda O Brien) followed, discussing the regional council’s reporting of the plant and poor rating, providing background around the abatement notices and infringements issued.

During the Q&A session, there was discussion about the odour scouting programme. It was confirmed that this is a proactive activity (not undertaken due to complaints). Regarding the plenum upgrade [biofilter media structure], once completed a preventative maintenance programme will be adopted to ensure the health and condition of the biofilter media.

The audience was reassured that the upcoming project work at the Seaview plant is being undertaken by professionals who are recognised in New Zealand as being subject matter experts. There was also high confidence that the allocated council funding for odour management will make a difference.

There was also assurance that the planned upgrades and technologies being proposed are particularly suitable for the Seaview plant and will be fast-tracked. Mr Hutchison also mentioned that covering aeration and clarifier tanks was not common in New Zealand or overseas and that the Seaview plant followed standard design.

Blair Johnson (Wellington Water) advised the meeting that the plant’s odour blaster had been moved to the sludge processing area to help minimise odour levels. Veolia meanwhile confirmed that the odour blaster was a neutralising spray (not disinfectant).

The plant’s capacity to handle future population growth was raised. Wellington Water commissioned a report in 2021 that identified equipment/assets that needed upsizing, and the proposed sludge dryer replacement project is a result of this. Otherwise, based on current forecasts, the plant has capacity for future decades.

During this session, Wellington Water acknowledged that communication about the plant can be better, and they are focused on addressing this moving forward.

Mana Whenua iwi expressed frustration at the current state of the plant. Wellington Water accepted the criticism and frustration and reasserted their aims to improve the plant’s performance. Recent effluent results are encouraging and show the plant is on track to achieving compliance. Improved pumping capacity at the plant was recognised in helping to slow stormwater ingress to the wastewater network.

Finally, there was questions about whether an App for reporting issues and complaints could be developed. Hutt City Councillor Brady Dyer advised that Council were in advanced stages towards developing an App. It is expected to be ready later this year. This will have built in GPS functionality  and enable the community to record issues with Council more easily.

Actions to be undertaken following feedback from the meeting.

  1. The presentation and FAQs are on the Wellington Water website here.
  2. Councillor Brady Dyer to check if a new Council App will include a field to select odour complaints, if not have it included.
  3. Wellington Water to make available peer reviews of designs for odour treatment upgrades
  4. Review the advice provided on signage near Waiwhetu discharge point and proximity to Waione Bridge for fishers - as part of the consent and propose actions (if any).
  5. Plant odour cannon- Wellington Water to provide the amount of neutralising spray that is used on a weekly basis.


Seaview Wastewater Plant Community Liaison Group Meeting - Dec 2023

Summary of Seaview Community Meeting – Tuesday, December 6, 2023

Pelorus House, Hutt Park, Lower Hutt -

Several dozen people attended a Wellington Water and Hutt City Council-hosted public meeting to discuss what Council and Wellington Water are planning to address the odour issue at the Seaview wastewater treatment plant.

Council and Wellington Water acknowledged that it's been unpleasant, inconvenient, and distressful for many who live in the vicinity.

Te Rūnanganui o Te Āti Awa ki te Upoko o Te Ika a Māui, Waiwhetu marae and Wellington Tenths Trust/Palmerston North Māori Reserve Trust were in attendance as were many residents. The Hutt Park Holiday Village (Top 10) also attended. Deputy Mayor Lewis, Councillors Edwards, Brown, Dyer and Mike Fisher Petone Community Board Chair also attended along with staff from HCC, WW and GWRC. Seaview Marina and other businesses were also in attendance. Andrew Freeman was the independent facilitator.

The presentation from Wellington Water explained the investigation undertaken to date and its outcome that biofilter media had reached the end of its lifespan and requires replacing. It was explained that an attempt to isolate and contain the first section of the biofilter as it was removed had not worked as hoped and resulted in the recent offensive odour.

Assurances were given by Council that we will do all we can to address the odour issue in the short and medium term.

Council is considering the draft Long Term Plan, which now has a significant investment of $13 million, to significantly improve the situation with replacement of aged equipment at the plant. This investment has been brought forward to the next three years.

Mana Whenua present requested a separate briefing and for improved communications with them. Residents and businesses expressed frustration with the time it is taking to address the issue and, in the meantime, having to live with the offensive smell.

Hutt Park Holiday Village was critical the work is being undertaken during their busiest period, reporting a significant number of negative online reviews and direct complaints from customers about the smell.

Wellington Water expects this work will be completed by 25 January by which time the odour is expected to have significantly abated.

Councillors recommended that residents continue to log complaints here (embed link) when they noticed the smell and encouraged them to make submissions to the Long Term Plan process currently before Council. An online survey to gather feedback will appear on this page on 2 April 2024 and remain open throughout April.



The Veolia team has successfully replaced the biofilter media in Cells 1 & 2 on 8 December. Both cells are now operational and treating the odorous gases as designed.

Excavation of the old media at cell three will commence this week with inspections completed before installing the new media.

Further updates will be provided as the project progresses.

Actions to be undertaken as a result of the feedback from the meeting.

  1. Regular (fortnightly) updates on the biofilter replacement work.
  2. An information sheet to be prepared for the Hutt Park Holiday Village to distribute to its customers as required. A staff member will be the key contact for the Top 10.
  3. Local signage advising of biofilter works erected.
  4. Direct contact made with Mana Whenua to discuss associated wastewater issues, specifically the overflow into Waiwhetū Stream which was raised during the meeting. An update on Wellington Water will be added to each quarterly hui with Mana Whenua.
  5. The presentation and FAQs are on the Wellington Water website here.